Features / Specs Dev Board Model: HW-537 GSM Module: SIMCom SIM800C (Refurbished Module – Tested & Guaranteed to be working) Guaranteed Firmware Version: 1418B08SIM800C24_BT Operating Voltage Range: 3.4 – 4.4VDC (1000uF Tantalum Capacitor on supply rail) Frequency Bands: Quad-Band (850/900/1800/1900MHz) Transmitting Power: Class 4 (2W) at GSM 850 and EGSM 900 / Class 1 (1W) at DCS 1800 and PCS 1900 GPRS Connectivity: GPRS multi-slot class 10 (Default) / GPRS multi-slot class 1~12 (Optional) GPRS Data Transfer Speed (Max): Downlink (85.6kbps) / Uplink (85.6kbps) Compatible AT Command Sets: 3GPP TS 27.007, 27.005 and SIMCOM enhanced AT Commands Comms Interface: UART (1200bps to 115200bps) (3.3V and 5V Compatible) Firmware Upgrade: Supported via Debug UART interface SIM Card Slot: Micro SIM GSM Antenna Connector: Male IPEX (1st Gen) Operating Current (Typical in Sleep Mode): 1.0mA Operating Temperature (Approx): -40℃ to 85℃ Indication LEDs: 2x Blue LEDs connected to the “VBAT” and “NETLIGHT” pins Bluetooth Specs: Support for Bluetooth 3.0 EDR / 10dbm Output Power Header Pin Pitch: 2.54mm Dimensions: ~(31.1mm x 26.7mm x 7.1mm) Note on Refurbished Modules:As you may have noticed, the SIMCom modules used on these breakout boards are classified as refurbished. What this ultimately means is that the modules have been de-soldered from another device that may or may not have been in operation, and re-soldered onto the brand new breakout boards with the rest of the components being brand new as well. The modules are still fully operational and original SIMCom modules, but may have some marks and scratches on their labels (This happens during de-soldering). Any similar SIMCom module sold at this price point will almost always be using a refurbished module. Some manufacturers have even gone to the lengths of reprinting the module label so that they seem new, but if you look closely you should be able to see the original label underneath. We would like to be completely transparent regarding all the items we sell which is why we think it is important that we explain the above in such detail. That being said, every SIMCom board we sell has undergone some basic quality control before we make them available to our customers. This includes a visual inspection, firmware re-flash to the above mentioned version, and a simple network registration check. Pin Description 5V-> Supply Voltage (5VDC @ > 1A Capability) V_TTL-> TTL Voltage level of connected device GND-> Ground TXD-> UART TX Pin (V_TTL Level) (Default Baud Rate is 9600bps) RXD-> UART RX Pin (V_TTL Level) (Default Baud Rate is 9600bps) DTR-> UART Data Terminal Ready SPKP-> Audio Positive Output SPKN-> Audio Negative Output MICN-> Audio Negative Input MICP-> Audio Positive Input RI-> UART Ring Indicator VRTC-> Power supply for RTC GND-> Ground PWX-> PWRKEY Pin (Pull low for > 1 second to turn the module on/off) GND-> Ground VBAT-> Power Supply Input of module (3.7V Lithium Battery Voltage Range) BT_ANT-> Bluetooth Antenna Connection Point GSM_ANT-> GSM Antenna Connection Point Resources SIM800C Hardware Design Manual v1.05 SIM800 AT Command Set v1.01